8 hydrology & hydrogeology - derryadd wind farm planning · 8 hydrology & hydrogeology 8.1...

Derryadd Wind Farm – EIAR

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8 HYDROLOGY & HYDROGEOLOGY

8.1 INTRODUCTION

This chapter describes the existing hydrological, hydrogeological and water quality characteristics at the

proposed Derryadd Wind Farm development site. This chapter also includes an assessment of the impact

on the water environment arising from the proposed 24 No. turbine development. The drainage of the

proposed development is also considered which includes proposed mitigation measures to reduce any

potential negative impacts associated with the construction and operation of the proposed development.

The proposed development is located approximately 3km east of Lanesborough, Co. Longford, 4km west

of Killashee, Co. Longford and 8km to the north of Newtowncashel Co. Longford. The wind farm is located

within the Mountdillon group of peat extraction bogs, Co. Longford.

Planning Permission is being sought from An Bord Pleanála for the installation of 24 No. wind turbines

with a nominal capacity of 4 MW per turbine or approximately 96 MW in total. The turbines will have a

blade tip height of a maximum of 185 metres(m) from the top of the foundation and will be accessible

from internal access routes within the Bord na Móna site. The full project description is included in Chapter

2 of this EIA Report (EIAR).

The proposed development is located in Bord na Móna’s Derryaroge, Derryadd, Lough Bannow and a

small section of Derryshannoge Bogs and is approximately 1900 hectares (ha) in area. The permanent

footprint of the proposed development measures approximately 51.8 hectares, which represents

approximately 2.7% of the primary study area.

The application includes for all necessary connections to the electricity grid. All elements of the Proposed

Development, including grid connection, have been assessed as part of this EIAR.

8.1.1 Statement of Authority

TOBIN Consulting Engineers (TOBIN) have completed this chapter. TOBIN Hydrologists and

hydrogeologists are intimately familiar with the site characteristics for the Derryadd Wind Farm, having

worked on wind farms at Lisheen and Bruckana set in similar ground conditions and water environment.

This chapter has been completed by Mr. John Dillon (BSc, MSc, MCIWM, PGeo), TOBIN Consulting

Engineers. John has 15 years of experience in hydrogeological/hydrological assessment for EIS/EIAR.

The author is appropriately experienced and capable of undertaking this assessment having worked on

wind farm projects in similar water environments including Bruckana Windfarm (42MW), Lisheen III


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Windfarm (24MW), Curragh Windfarm (18.4 MW). John has experience in the

hydrogeological/hydrological assessment and supervision of powerline projects including Cloon –

Lanesboro 110kv uprate, North South 400kV interconnector, Moneypoint substation and Laois Kilkenny

400/110 kV substation. Cathal Kelly B.E, MIEI, MICE has also been responsible for carrying out hydraulic

modelling of Flood Risk Assessment. Cathal has completed a large number of flood risk assessment for

flood relief schemes, windfarms, solar farms, residential developments and commercial developments.

8.1.2 Scope of Assessment

The scope of the assessment undertaken was set out as follows:

1. Characterise the hydrological and hydrogeological baseline conditions of the existing

environment based on a desktop study and site investigation.

2. Identify the possible impacts of the proposed development during construction and operation of

the project on the receiving hydrological and hydrogeological environment.

3. Develop mitigation measures to reduce or eliminate the identified negative impacts.

4. Identify any residual impacts after mitigation measures are implemented.

8.2 METHODOLOGY

An examination of the existing hydrological regime was carried out through a combination of consultation

with relevant authorities, a desktop review of hydrological resource and site-specific fieldwork; these

elements are described further below.

The assessment of the water environment consisted of the following:

• A desk study of available information including a review of site investigations, relating to surface

water and groundwater, undertaken within or adjacent to the site;

• A walk-over of the site and surrounding area;

• Groundwater level monitoring;

• Surface water quality monitoring;

• Interpretation of all data to establish the baseline environment, and

Assessment of flood risk.

The following guidelines have been taken into consideration in the preparation of this EIAR Report:

• “Advice Notes on Current Practice in the Preparation of Environmental Impact Statements” (EPA,

September 2003);

• “Guidelines on the Information to be contained in Environmental Impact Statements” (EPA, 2002);


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• “Draft Guidelines on the Information to be contained in Environmental Impact Assessment

Reports” (EPA, 2017); and

• “Draft Advice Notes on Preparing Environmental Impact Statements” (EPA, September 2015).

The guidelines and recommendations of the Institute of Geologists of Ireland (IGI) publication ‘Geology

in Environmental Impact Statements – A Guide’ (2002) and the IGI Guidelines for the Preparation of Soils,

Geology and Hydrogeology Chapters of Environmental Impact Statements (2013) were also taken into

account in the preparation of this Chapter.

8.2.1 Legislative / Guidance Review

An evaluation of the proposed development was carried out in relation to the relevant European and

National legislation and other statutory policies and guidance. The following legislation was considered

as part of this impact evaluation.

• S.I. No. 94 of 1997 Quality of Salmon Water Regulations;

• SI 272 of 2009 Surface Water Regulations;

• SI 9 of 2014 Groundwater Regulations;

• Consolidated EIA Directive 2011/92/EU and 2014/52/EU;

• European Communities (Water Policy) Regulations 2003 [S.I. No. 722/2003];

• Waste Management Acts 1996 as amended;

• European Communities Environmental Objectives (Groundwater) Regulations 2010 [S.I. No.

9/2010];

• European Communities (Environmental Impact Assessment) (Amendment) Regulations, 2001

[S.I. No. 538/2001];

• European Communities Environmental Objectives (Groundwater) Regulations 2010 (S.I. 9 of

2010);

• Groundwater Directives (80/68/EEC) and (2006/118/EC); and

• Water Framework Directive (2000/60/EEC).

The following documents were consulted in preparation of this report as they pertain to hydrogeology and

hydrology:

• Longford County Development Plan 2015 – 2021.

In addition to the Regulations and Guidelines above, this EIAR has been prepared with cognisance to the

“Wind Energy Development Guidelines for Planning Authorities (2006)”, the proposed draft revisions to


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these guidelines (December 2013) and the DCCAE (2017) preferred draft approach - Review of the Wind

Energy Development Guidelines 2006.

8.2.2 Desktop Study

The desk top study involved a review of all available information, datasets and documentation sources

pertaining to the site’s natural environment.

Information retained by the Geological Survey of Ireland (GSI), the Office of Public Works (OPW) and

EPA was accessed to provide the hydrological and hydrogeological setting of the site. Relevant

documents and datasets used to provide the setting of the site included EPA Water Quality Data,

topography maps and GSI Hydrogeological Data.

The following sources of information were utilised to establish the baseline environment:

• The Geological Survey of Ireland (GSI) groundwater records for the area were inspected, with

reference to hydrology and hydrogeology;

• Office of Public Works (OPW) flood mapping;

• Catchment Flood Risk Assessment and Management (CFRAM) and Preliminary Flood Risk

(PFRA) Map data;

• EPA water quality monitoring data for watercourses in the area;

• Results from the chemical analysis of water samples taken in 2015 - 2018;

• EPA Water Framework Directive Monitoring Programme; and

• Information from the River Basin Management Plan for the Shannon River Basin District

(SHIRBD).

8.2.3 Field Surveys

Field work involved:

• A walkover survey of the site to identify hydrological features on site, wet ground, drainage

patterns and distribution, exposures, drains etc;

• Peat Probes in 2017 and 2018;

• Trial Pitting in 2017 and 2018;

• Borehole testing in 2017, and

• Field analysis of water samples in 2017 and 2018.


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Following the field surveys, the results were reviewed in ArcGIS software in conjunction with publicly

available hydrological and hydrogeological data from the GSI, EPA and OPW. Various maps were

produced, representing a graphical interpretation of the field results.

TOBIN Consulting Engineers carried out an investigation from April 2016 to May 2018, to assess the

water environment in the vicinity of the proposed development.

Consultation with various state agencies and environmental Non-Governmental Organisations (NGO‘s)

was undertaken to inform the EIA. All project consultation is detailed in Chapter 1 of the EIAR and all

responses received are summarised in Chapter 1. Consultees were informed of updates to the site layout,

as appropriate. Consultation letters were sent (September 2016, April/ May 2017 and April 2018) to the

following key parties relevant to this chapter:

• An Bord Pleanála;

• Geological Survey Ireland;

• Irish Peatland Conservation Council; and

• Longford County Council.


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Department Comments and

Recommendations

EIAR Chapter /Section

An Bord Pleanala Ensure connectivity of the site is

considered in detail for Ecology,

Water, Turloughs, Wetlands,

karst features etc. in the local

and regional study area.

Chapters 6, 7 and 8, NIS

GSI

There are no (GSI) well data

within the perimeter of the

proposed wind farm, but a few

exist on the edge.

There are no landslide records

within the perimeter of the

proposed wind farm. Please

note that the dedicated viewer

http://spatial.dcenr.gov.ie/Geolo

gicalSurvey/LandslidesViewer/i

ndex.html is being upgraded and

should be live in the autumn.

Chapter 7

Irish Peatland Conservation

Council

Lough Bannow pNHA habitats

are particularly sensitive to any

change in water quality and run

off. All precautions must be met

to ensure no degradation occurs

on the site as a result of this

development.

Lough Ree SAC

Lough Ree SAC/SPA is

downgradient from the site.

Chapter 6


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A site investigation programme was undertaken at the subject site to acquire site specific data on the

nature and characteristics of the underlying ground. The site investigation programme was undertaken

in accordance with the British Standard BS 5390 (Site Investigation – Code of Practice). This enabled

the site investigation programme to be undertaken in a systematic manner and provided details of a

process of site investigations and interpretation methodology to characterise the underlying groundwater

conditions.

IPCC would like for the EIS to

assess any potential

watercourses linking the

proposed development site to

Lough Ree SAC which could be

adversely affected by any

change in water quality that

might result from large scale

construction.

.

Longford County Council Impact on environmental

designations – including Natural

Heritage Areas, Special

Protection Areas, Special Areas

of Conservation,

Drainage design to be included

(current and future), and

anticipated water table impacts.

Particular regard should be had

to Section 6.2.2.7 Inland Lakes

and Waterways and the Policies

ILW1 to ILW17 relating to the

protection of Longford’s Inland

Waterways.

Chapter 6 and Section 8.4.


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A total of 5(no.) shell & auger boreholes were drilled at Derryadd Bog -see Figure 8.6. These boreholes,

labelled RC1 to RC5, were drilled at a diameter of 200mm to depths varying between 15 and 20m below

ground level. The drilling was carried out by Irish Drilling Limited under the supervision of TOBIN.

All five of the air rotary drilled boreholes, were retrofitted with groundwater monitoring standpipes. These

installations comprised of narrow diameter piezometer tubes (50mm ID, 54mm OD), with granular

material installed as a filter pack in the annulus surrounding the piezometer. A seal of concrete overlying

bentonite was installed at the top of the installations above the filter pack to prevent surface water

entering the borehole via the annulus. Slotted standpipe was installed beneath the seal to allow ingress

of groundwater to the piezometer. Upstanding steel covers were installed at the five monitoring points.

Slug (permeability) tests were undertaken in RC3 to RC4 to provide an estimate of the hydraulic

conductivity of the bedrock formation. It consists of measuring the static water level (head) in the well,

then introducing a near instantaneous change in water level, and measuring the change in water level

over time until the water level returns to the original static water level. The instantaneous change in head

can be achieved by adding or removing a volume of water or solid into the well.

A slug test provides a very local estimate of hydraulic conductivity or transmissivity in the near vicinity of

a well. As for pumping aquifer tests, several analytical methods have been developed for the analysis of

slug tests. Hvorslev (1951) and Bouwer and Rice (1976) were used to analysis the data. The method of

testing involved two different procedures, the first involved undertaking a rising head permeability test

(Slug Test) and the second method of testing involved recording the recovery of water levels following

purging of the borehole standpipe. Hydraulic characteristics can be determined by monitoring the

changes in water levels over recorded time.

8.2.4 Significance and Magnitude Criteria

The significance of effects of the proposed development has been assessed in accordance with the EPA

guidance document Draft Guidelines on the information to be contained in Environmental Impact

Assessment Reports (EIAR), Draft, August 2017122.

Table 1.1, included in Chapter 1, Section 1.8.2 of this EIAR, is taken from the EPA document. This table

outlines guidance for describing the quality and significance of effects and informs the assessment of the

relevant potential impacts of the proposed development within this chapter.

122 https://www.epa.ie/pubs/advice/ea/EPA%20EIAR%20Guidelines.pdf


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8.3 EXISTING ENVIRONMENT

8.3.1 Desk Based Studies

On a regional scale, the site at Derryadd and its environs is in the Shannon Hydrometric Area and

Catchment. The delineation of the sub-catchments and general area of confluence is shown in Figure 8.1

‘Regional Catchment Delineation’.

The proposed development site is located within the Shannon International River Basin District

(SHIRBD). At a local scale, the proposed wind farm is located between the Ballynakill River to the east

and the Lough Bannow River to the west of the wind farm. All rivers ultimately discharge to the River

Shannon. A canalised stream is located at the southern end of Derryadd bog discharges to the Lough

Bannow stream.

The topography of the site is relatively flat with elevations ranging from 37mAOD to 59mAOD.The general

topography varies approximately from 45 to 59 mAOD to the south of the study area (Lough Bannow

Bog) and between 37 and 47mAOD in the Derryadd and Derryaroge Bogs. Further details are included

in Chapter 7 – Lands, Soils and Geology.

Surface Water Hydrology

The purpose of this section is to describe the surface water environment including the following:

• Catchments;

• Site surface water features and drainage;

• Flood assessment;

• Assessment of hydrometric data;

• Surface water abstractions within the catchment of the site; and

• Surface water quality.

Catchments

A catchment is simply defined as an area contributing water to a river and its tributaries, with all the water

ultimately running off to a single outlet. The catchment boundary is the line dividing land where surface

drainage flows toward a given stream from land where it drains into a separate stream.

The regional natural surface water drainage pattern, in the environs of the proposed Derryadd Wind Farm

development site is shown on Figure 8.1 ‘Regional Catchment Delineation’. The proposed development


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site is located within the River Shannon catchment, located within the Shannon River Basin District and

upstream of the Lough Ree Special Area of Conservation (SAC) (Site Code 00440).

Figure 8.2 depicts Surface Water Features/Local Catchment Delineation in relation to site area’ which

includes a significant number of unnamed streams although EPA reference numbers have been applied

for identification purposes. The proposed development is not located in a delineated area for action as

set out in the 2018-2021 National River Basin Management Plan. The Royal Canal, located to the east

of the proposed development is not hydrologically linked to the proposed development site.

Each of the streams flowing through or adjacent to the site has its own sub-catchment area. The

delineation of these catchment boundaries is shown in Figure 8.2 and Figure 8.3 (Figures 8.3A-8.3C).

The EIAR study area comprises of approximately 1900ha and has several surface water features in the

region of the site. The rivers surrounding the site all discharge to the River Shannon or to Lough Ree.

The main regional surface water features include the following:

• The Ballynakill River is located to the north and west of the Derryadd and Derryaroge bog;

• The Lough Bannow Stream and its tributaries are located to the east of Lough Bannow and flows

Derryadd bog);

• The Ballynakill River and Lough Bannow Stream discharge to the River Shannon, north of

Lanesborough; and

• The Ledwithstown River or Bilberry River flows to the south of Lough Bannow bog and discharges

to Lough Ree.

A number of natural tributaries that flow into these rivers are located close to the proposed development

site. The Derrygeel stream (EPA Ref: 26_1494), rises close to the northern area of the development and

continues north joining additional tributaries before its confluence with the Ballynakill River. On the 15th

May 2018, the channel of the Derrygeel stream (26_593) was dry where it made its way into the site. This

stream had accumulated some flow by the time it exited the site boundaries.

Approximately 4km further to the west of the Bord na Móna landholding, a more karstic flow regime

occurs. The landscape between Lough Ree and Lough Bannow Stream comprises a plateau (broad

interfluve) which is gently undulating between 43-88 mOD. Few surface water features occur in this

plateau however small sinking streams and turloughs occur to the south of the area. Two turloughs,

Cordara Turlough and Fortwilliam Turlough occur 3.5km and 4.7km to the south west of Turbine 17,

respectively. Cordara Turlough is connected to Fortwilliam Turlough via a sinking stream and

excavated/man made drainage ditch. This stream and Cordara Turlough are dry during the summer


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months with a permanent water body occurring at Fortwilliam. During the January 2017 and February

2018 site visits the Cordara Turlough was in flood. Water from Cordara Turlough discharges via surface

water and groundwater to Fortwilliam Turlough. Discharge from Fortwilliam Turlough is controlled via a

sinkhole located on the western lip of the turlough.

Fallan (River)

Camlin (River)

Shannon

(Rive

r)

Bilberry (River)

Hind (River)

Feorish (River)

Scram

oge (

River)

Inny (River)

Clooneigh (River)

L o n g f o r dL o n g f o r d

DERRYADD WIND FARM

REGIONAL CATCHMENTDELINEATION

F.Healy J. Dillon January 2019D. Grehan

Figure 8.1 A

Scale @ A3:

Issue Date Description By Chkd.

Client:

Project:

Title:

Prepared by: Checked: Date:

Project Director:

Consulting, Civil and Structural Engineers,Block 10-4, Blanchardstown Corporate Park, Dublin 15, Ireland.tel: +353-(0)1-8030406fax:+353-(0)1-8030409e-mail: [email protected]

Issue:No part of this document may be reproduced or transmitted in any form or stored in any retrieval system of any nature without the written permission of Patrick J. Tobin & Co. Ltd. as copyright holder except as agreed for use on the project for which the document was originally issued.

1:80,000

A

NE

E

SE

S

SW

W

NWN

DECLAN CUNNINGHAM 2004

Legend

River

Ballynakill River

Lough Bannow Stream

1. FIGURED DIMENSIONS ONLY TO BE TAKEN FROM THIS DRAWING2. ALL DRAWINGS TO BE CHECKED BY THE CONTRACTOR ON SITE3. ENGINEER TO BE INFORMED OF ANY DISCREPANCIES BEFORE ANY WORK COMMENCES4. ALL LEVELS RELATE TO ORDNANCE SURVEY DATUM AT MALIN HEAD

NOTES

Ordnance Survey Ireland Licence No EN 0016019 ©Ordnance Survey Ireland and Government of Ireland

0 2 4 61Kilometres

County Boundary

Planning Application Boundary

Jan 2018 FH JDFinal Issue

9

87

6

54

3

21

24

23

2221

201918

17

161514

13

12

1110

26_410226_4116

26_625

26_3

571

26_5

73

26_3102

26_3545

26_3544

26_6

92

26_872

26_3103

26_3735

26_291726

_272

526_1485

26_2020 26_2

299

26_670

26_3871

26_604

26_807

26_3938

26_64826_

3078

26_3101

26_1494

26_1537

26_3574

26_1151

26_617

26_3

935

26_3650

26_627

26_3083

26_3100

26_3939

26_2726

26_1

483

26_1516

26_593

26_4074

26_2818

26_146926_524

26_1515

26_957

26_280

26_407

7

26_871

26_3610


DERRYADD WIND FARM

Surface Water Features/Local Catchment Delineation

D. Grehan

Figure 8.2 A

Scale @ A3:


Client:

Project:

Title:


Project Director:



1:50,000

NE

E

SE

S

SW

W

NWN


0 1 2 3 40.5Kilometers


NOTES


Legend

RiverCounty Boundary

River Segment Code: 26_XXXXProposed Turbine Locations


A Jan 2018 FH JDFinal Issue

F.Healy J. Dillon January 2019


9

8

7

6

5

4

3

2

1

11

10


DERRYADD WIND FARM

Existing Surface Water Features& Drainage within the

Site Boundary - Derryarogue

F. Healy J. Dillon January 2019D. Grehan

Figure 8.3A A

Scale @ A3:


Client:

Project:

Title:


Project Director:



1:15,000

A Jan 2019 FH JD

NE

E

SE

S

SW

W

NWN


Final Issue

Infrastructure

Legend

County Boundary


Drainage LayoutProposed Turbine Locations

River

0 10.5Kilometres


NOTES


$+ Pump stations

17

16

1514

13

12

11

10


DERRYADD WIND FARM


Site Boundary - Derryadd

F. Healy J. DillonD. Grehan

Figure 8.3B A

Scale @ A3:


Client:

Project:

Title:


Project Director:



1:16,000

NE

E

SE

S

SW

W

NWN


Infrastructure

Legend

County Boundary



River

0 10.5Kilometres


NOTES


January 2019


$+ Pump stations

24

23

22

21

20

19

18

16

15

14


DERRYADD WIND FARM


Site Boundary - Lough Bannow


Figure 8.3C A

Scale @ A3:


Client:

Project:

Title:


Project Director:



1:15,000

NE

E

SE

S

SW

W

NWN


Infrastructure

Legend

County Boundary



River

January 2019


0 10.5Kilometres


NOTES


$+ Pump stations


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Surface Water Features and Drainage within the Site Boundary

The proposed wind farm is located within an operating peat extraction site. An extensive network of

drainage channels is present throughout the peatland which is currently operated under IPC licence

P0504-01 Mountdillon bog group. The drainage hierarchy is outlined below in Diagram 8.1.

Extensive site drains and main drains are present within the Bord na Móna property. The site and main

drains within the currently IPC licenced site both store water and transmit it to main drains and ultimately

to the settlement ponds. The storage capacity of run-off water in the drainage network lessens the impact

of sediment mobilisation to receiving water, due to the low velocity of the water and the retention time in

the drains. Final settlement occurs in the settlement ponds before discharging to the adjacent drains and

streams See the conceptual sketch below.

Diagram 8.1 Drainage hierarchy on peatlands.

Three streams/drainage channels were identified to be flowing through or adjacent to the proposed wind

farm site (see Figure 8.2). The site and adjacent lands also include many man-made drains which flow

to the watercourses identified in Figure 8.2 and assist in the drainage of peatland, reclaimed peatland

areas under agricultural land use and forestry.

Flood Assessment

The OPW ‘Flood Hazard Database’ was used to obtain information on historical flooding events within

the proposed development area. No flood events were identified within 1km of the proposed development.

Site drains Main DrainsSettlement

PondsExternal Streams

and drains


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The national programme of Catchment Flood Risk Assessment and Management (CFRAM) Studies

comprises the execution of three parts:

(1) Preliminary Flood Risk Assessments;

(2) Flood Hazard Mapping; and

(3) The development of Flood Risk Management Plans.

The OPW initially produced a series of maps to assist in the development of the Preliminary Flood Risk

Assessment (PFRA) throughout the country. These maps were produced as part of a desktop study of

several sources. In July 2011, the Office of Public Works (OPW) published a series of maps showing the

estimated 100-year flood plain from the Preliminary Flood Risk Assessment (PFRA) study. This

information was used to establish the current baseline conditions. Areas of pluvial flooding were noted

on the OPW PFRA mapping, but no records of fluvial flooding were noted for the proposed turbine

locations. The PFRA study maps (i.e. the MyPlan.ie viewer) were reviewed and the proposed site is not

located within a groundwater flood risk zone. There is no evidence of historic groundwater flooding at the

site.

The proposed development site is not located in a flood prone area (Flood Zone A or B) based on the

preliminary flood risk assessment (PFRA) maps. This dataset suggests that fluvial flooding does not occur

at proposed turbine or substation locations. Based on the information available and a site-specific risk

assessment it is not considered a flood risk – See Appendix 8.1.

Substantial areas of the proposed development and surrounding area have been artificially drained to

enable industrial harvesting of peat. The carefully maintained network of drainage ditches effectively drain

the proposed development site and surrounding area.

Drainage management works carried out as part of site activities maintain drainage systems within the

proposed development site and reduce the potential for surface water ponding. Data on historical flooding

is limited but records do not indicate that flooding occurs on the downgradient streams. Small areas of

pluvial flooding occur within the site however improved drainage and water management has limited the

potential for flooding in the three bogs. The drainage within the site is controlled by pumping from the site

in accordance with the IPC licence. No incidents of flooding were noted at the site.

Assessment of Hydrometric Data

As outlined previously, the natural surface water drainage pattern in the environs of the proposed

development site is shown in Figure 8.2. The streams are identified as follows:


431

Derryaroge Bog (Location of Turbines 1-9)

The proposed turbines T1-T9 and associated roads are located within the catchment of two streams:

Stream 26_1494 located to the northern west of the Derryaroge site; and stream 26_3574 form the part

of the eastern boundary of the Derryaroge site. The catchment area for each stream was estimated using

the EPA’s online database (gis.epa.ie/Envision) and geographic contours available from OS maps.

Derryadd Bog (Location of Turbines 10-17)

Three streams were identified as flowing through or adjacent to the proposed turbines T10-T17. Stream

26_625 is located to the east of turbines T10-T17; and streams 26_3871 and 26_593 form the western

boundary.

The proposed substations and overhead/underground powerlines are located in the Lough Bannow

stream catchment (26_3871 and 26_593).

• Substation Option A is located to the south of the Mountdillon works. Substation Option A is

within the catchment of Stream 26_3871, which discharges to the Lough Bannow stream

approximately 5km downgradient of the Substation Option A; and

• Substation Option B is within the catchment of Stream 26_593, which discharges to the Lough

Bannow stream approximately 1km downgradient of the substation. Four possible borrow pits

are identified within the Lough Bannow stream catchment.

The catchment area for each stream was estimated using the EPA’s online database (gis.epa.ie/Envision)

and geographic contours available from OS maps.

Lough Bannow Bog (Location of Turbines 18-24)

Two streams were identified as flowing adjacent to the proposed turbines T18-T24. Stream 26_625 is

located to the north of turbines 18-24 and Stream 26_3735 located to the south. It was noted that there

were no hydrometric stations located in the immediate environs of the proposed site. Although

hydrometric stations do exist on watercourses downstream of the development, they include flows coming

from a number of different tributaries (gis.epa.ie/Envision). As such, they are not representative of the

actual flows occurring at the site.


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Surface Water Abstractions within the Site

There are currently no known surface water abstractions from the streams adjacent to the site or from

any surface water features <10km from the site boundary.

Surface Water Quality

Off-Site Surface Water Quality:

The Environmental Protection Agency (EPA) regularly monitors water bodies in Ireland as part of their

remit under the Water Framework Directive (WFD) (2000/60/EC), which requires that rivers are

maintained or restored to good/ favourable status. Quality of watercourses are assessed in terms of 4

No. quality classes; ‘unpolluted’ (Class A), ‘slightly polluted’ (Class B), ‘moderately polluted’ (Class C)

and ‘seriously polluted’ (Class D). These water quality classes and the water quality monitoring

programme are described in the EPA publication ‘Water Quality in Ireland, 2016’. The water quality

assessments are largely based on biological surveys. Biological Quality Ratings or Biotic Indices (Q

values) ranging from Q1 to Q5 are defined as part of the biological river quality classification system. The

relationship of these indices to the water quality classes defined above, are set out in Table 8.1 below.

Table 8.1: Relationship between Biotic Indices and Water Quality Classes

Biotic Index Quality Status Quality Class

Q5, 4-5, 4 Unpolluted Class A

Q3-4 Slightly Polluted Class B

Q3, 2-3 Moderately Polluted Class C

Q2, 1-2, 1 Seriously Polluted Class D

There are no EPA or WFD monitoring locations on the streams adjacent to the proposed site. However,

samples were recorded on the River Shannon 1km downgradient of Lanesbourogh Power Station and

4km upgradient at Termonbarry village. The most recent EPA results for 2014 indicates these monitoring

points indicate that the quality of water at this location is Q3 – ‘Moderately Polluted’ and Q3-4 – ‘Slightly

Polluted’ (or Poor Status based on the classification in Figure 8.4 ‘EPA Surface Water Monitoring

Locations’). Samples were also recorded on the Farran River located 5km to the west of the proposed

development. The most recent EPA results for these monitoring points (West of Curry Bridge) indicate

that the quality of water at this location are Q3 – Moderately polluted and Q3-4 – ‘Slightly Polluted’ (or

Poor Status based on the classification in ‘EPA Water Quality Indicators123’).

123 EPA Water Quality Indicators 2016


433

Table 8.2: EPA Monitoring of Biological Quality of Waters on the River Shannon Upper

Location W of Curry Bridge 1km downstream of

Termonbarry

Ballyleague Br

Lanesboro

River Farran Shannon Shannon

Station Code RS2680100040 RS26S021530 RS26S021600

-

2014 Q3-4 Q3-4 Q3

2011 Q3-4 Q4 Q3-4

2008 Q3-4 Q3-4 -

2005 Q3-4 - Q3

The majority of EPA monitoring points on the River Shannon indicate that the overall water quality in this

area is ‘Moderately Polluted’ and that the water quality upstream of the development is ‘Slightly Polluted’.

The overall status of surface water/rivers in the vicinity of the proposed site is ‘Poor Status’. This

classification is based on a low macroinvertebrate value (Q-Value) according to www.wfdireland.ie.

The Water Framework Directive (WFD) classified the surface waters in the southern area of the proposed

Derryadd Wind Farm as Class 1a - indicating that rivers here are at risk of not achieving good status by

2015 (www.epa.ie). The northern section of the development site is classified as Class 1b – Possibly at

risk of not achieving good status. This risk classification is based on a Q Class/EPA Diffuse Model or

worst case of Point and Diffuse (2008) (www.wfdireland.ie).

8.3.2 Field Based Studies

Site Specific Surface Water Quality:

Surface water monitoring is conducted at the Mountdillon IPC Licence site on a regular basis as part of

the IPC Licence. As shown in Table 8.3 and 8.4, results for the parameters tested were within the

recommended discharge limits. All samples were taken from surface water channels during periods of

low flow (low dilution factor), these results are as expected for the natural background environment in this

area (in particular, elevated levels of ammonia and suspended solids would be expected in a peat

soil/subsoil environment). These results provide a baseline set of results which can be used for

comparative studies during the lifetime of the proposed wind farm.

Field monitoring results from January 2017 and March 2018 are included in Table 8.5 and 8.6 respectively

and shown on Figure 8.5. The low conductivity values indicate that the Ballynakill and Lough Bannow

River are predominately fed by surface water runoff. Approximately 3km to the west of the proposed

http://www.wfdireland.ie/



434

development, higher conductivity values on a tributary to Lough Bannow River (26_280) and Fortwilliam

stream indicate an increasing component of groundwater flow. The St Martins springs on the shores of

Lough Ree have a similar conductivity value to Fortwilliam Turlough.


435

Table 8.3: Surface Water Analysis Mountdillon Bog Group IPC (2016 AER DATA)

Table 8.4: Surface Water Analysis Mountdillon Bog Group IPC (2017 AER DATA)

Bord na Mona Mountdillon

IPPC Licence P0504-01

X Y Bog SW Monitoring Sampled pH SS TS Ammonia TP COD Colour

205264 266930 Derryadd SW-72 Q1 17 20/03/2017 7.8 8 362 0.58 0.05 59 122

205704 264986 Derryadd SW-73 Q1 17 20/03/2017 7.7 12 349 1.1 0.05 52 126

206484 264718 Lough Bannow SW-74 Q1 17 20/03/2017 7.9 7 306 0.29 0.05 52 142

209521 261718 Lough Bannow SW-77 Q2 17 29/05/2017 7.9 14 292 0.11 0.05 41 111

207855 263302 Lough Bannow SW-78 Q2 17 29/05/2017 7.8 5 296 0.3 0.05 23 115

205264 266930 Derryadd SW-72 Q3 17 27/07/2017 7.6 5 256 0.43 0.06 67 177

204007 264128 Derryshannoge SW-81 Q3 17 27/07/2017 7.8 21 282 0.16 0.05 68 147

Bord na Mona Mountdillon

IPPC Licence P0504-01

X Y Bog SW Monitoring Sampled pH SS TS Ammonia TP COD Colour

204806 268664 Derryadd SW-68 Q1 16 14/03/2016 7.8 5 353 0.43 0.07 40 108

207219 268277 Derryadd SW-70 Q1 16 15/03/2016 7.5 5 242 0.16 0.05 50 193

207139 268700 Derryadd SW-71 Q2 16 09/06/2016 7.7 5 350 0.02 0.05 37 159

209437 266842 Lough Bannow SW-76 Q2 16 09/06/2016 7.8 5 372 0.34 0.05 31 123

209521 261718 Lough Bannow SW-77 Q2 16 09/06/2016 7.5 34 310 0.06 0.09 54 200

207855 263302 Lough Bannow SW-78 Q2 16 09/06/2016 7.8 5 418 0.02 0.05 37 127


204286 272641 Derryaroge SW-35 Q3 16 12/09/2016 6.7 6 150 0.07 0.46 115 301

203400 272510 Derryaroge SW-36 Q4 16 12/12/2016 7.5 12 420 2.9 0.01 58 45


436





437

Table 8.5 Surface Water Analysis Derryadd Wind Farm 17/01/17

ID Location Temp Conductivity pH TSS

Units oC µS/cm pH units mg/l

S1 Lough Bannow stream 26_1150 8.2 390 6.7 <10


S3 Lough Bannow stream 26_280 8.5 460 7 <10

S4 Cordara Turlough 9.5 426 7 <10

S5 Fortwilliam stream inflow 10 597 7.1 <10

S6 St Martins Springs 10.5 590 7 <10

S7 Derryadd outflow to Ballynakill Stream 7.5 335 7.1 <10

S8 Ballynakill Stream upgradient of Derryadd outflow 8.2 399 7 <10

S9 Ballynakill Stream 26_625 at R398 road crossing 8.6 361 7 <10

S10 Ballynakill Stream 26_3102 7.8 359 6.9 <10

S11 Derryaroge outflow to River Shannon 8 389 6.9 <10

S12 Derryaroge bog, within site drainage ditch 8.6 347 6.9 <10


Table 8.6 Surface Water Analysis Derryadd Wind Farm 17/05/2018

ID Location Temp Conductivity

Units oC µS/cm

S1 Lough Bannow stream 26_1150 12.1 399



S4 Cordara Turlough DRY 445

S5 Fortwilliam stream inflow 10.7 676

S6 St Martin’s Springs 10.8 666

S7 Derryadd outflow to Ballynakill Stream 12.1 337

S8 Ballynakill Stream upgradient of Derryadd outflow 12.5 416

S9 Ballynakill Stream 26_625 at R398 road crossing 12.0 372

S10 Ballynakill Stream 26_3102 12.4 361

S11 Derryaroge outflow to River Shannon 12.4 405


438

S12 Derryaroge bog, within site drainage ditch 12.5 355


Br W of Curry Q3-4

Br S of Kilmore Upper Q3-4

Ballyleague Br Lanesboro Q3

9

8

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54

3

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161514

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DERRYADD WIND FARM

EPA Surface WaterMonitoring Locations


Figure 8.4 A

Scale @ A3:


Client:

Project:

Title:


Project Director:



1:50,000

NE

E

SE

S

SW

W

NWN


NOTES

Legend

0 1 2 3 40.5Kilometres



RiverPlanning Application Boundary

County Boundarypo Water Quality Monitoring Stations

January 2019


&(

&(

&(

&(&(

&(

&(&(

&(

&(

&(&(

&(&(

&(

S9

S8S7

S6 S5 S4

S3

S2

S1

S15

S14 S13

S11S12

S10

DERRYADD WIND FARM

Surface Water Monitoring Locations2017 and 2018


Figure 8.5 A

Scale @ A3:


Client:

Project:

Title:


Project Director:



1:50,000

NE

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SE

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SW

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NOTES


Legend

River

&(Surface Water Monitoring2017 & 2018


January 2019


RC 3

RC 2

RC 5RC 4

RC 1

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RkcLl

Pl

DERRYADD WIND FARM

Aquifer Classifications

F. Healy J. Dillon January 2019D. Grehan

Figure 8.6 A

Scale @ A3:


Client:

Project:

Title:


Project Director:



1:40,000

NE

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SE

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Legend

0 1 2 30.5Kilometres


NOTES


RiverPlanning Application Boundary


AquiferLkLlPlRkc

Karst FeaturesBoreholeEnclosed DepressionSpringSwallow HoleTurlough

Proposed Turbine LocationsCounty Boundary


442

Hydrogeology/Groundwater

8.3.2.1.1 Existing Groundwater Quality

The Water Framework Directive (www.wfdireland.ie) describes the groundwater quality status of the

proposed development in this area as ‘Good’. These classifications are based on an assessment of the

point and diffuse sources in the area that may affect the groundwater quality. The groundwater in this

area was found to have been particularly at risk from Diffuse source pollution (DIF).

8.3.2.1.2 Aquifer Potential and Characteristics

Reference to the National Aquifer Map prepared by the GSI (www.GSI.ie) indicates that there are three

types of Bedrock Aquifer underlying the proposed site. The Derryaroge and Derryadd Bogs are underlain

by a Regionally Important Aquifer – (Conduit) Karstified (Rkc). The Lough Bannow Bog and

Derryshannoge Bog are underlain by a Locally Important Aquifer, which is Moderately Productive in local

zones (Ll). The various aquifer classifications are illustrated in Figure 8.6 ‘Aquifer Classifications’.

The subsoil deposits overlying the bedrock are not considered to be of sufficient lateral extent or depth

to represent an aquifer body and are mainly comprised of peat deposits and low permeability limestone

till, and alluvial/lacustrine deposits with occasional lenses of sand and gravel (refer to Chapter 7, Lands,

Soil and Geology for further information).

Summarised below in Table 8.7, are the aquifer characteristics of the underlying aquifer and surrounding

aquifers.

Table 8.7: Bedrock Aquifer Classification and Characteristics

Aquifer Classification Permeability/Flow Mechanism Karst Features

Regionally Important

(Rkc)

Regionally Important Aquifer - Karstified

(conduit)

Yes

Locally Important (LI) Productive only in Local Zones No

Groundwater flow paths within the aquifer are expected to generally follow the local surface water

catchments. Adjacent to the rivers, water levels will be closer to ground level.

The EPA report that bedrock is close to the surface within 1km of the surrounding area of the proposed

site. No significant dissolution features (i.e. karst) were observed from visual appraisal of the proposed

site and no karst features are recorded within the GSI Karst Database of Ireland within a 1km radius of

the proposed development site. However, a turlough is located 3.6km to the southwest of T17.


http://www.gsi.ie/


443

8.3.2.1.3 Groundwater Vulnerability

Groundwater vulnerability represents the intrinsic geological and hydrogeological characteristics that

determine how easily groundwater may be contaminated by activities at the surface. Vulnerability

depends on the quantity of contaminants that can reach the groundwater, the time taken by water to

infiltrate to the water table and the attenuating capacity of the geological deposits through which the water

travels.

These factors are controlled by the types of subsoils that overlie the groundwater, the way in which the

contaminants recharge the geological deposits (whether point or diffuse) and the unsaturated thickness

of geological deposits from the point of contaminant discharge.

The groundwater vulnerability throughout the proposed site ranges from L (Low) to H (High). Figure 8.7

‘Groundwater Vulnerability Map’ illustrates the vulnerability classifications for this area. Site investigation

and geophysics data would indicate that extensive subsoil deposits occur at most turbine locations.

Shallow subsoils are noted at T5, T11 and T14.

Table 8.8: Groundwater Vulnerability Categories

Sensitivity Hydrogeological Conditions

Subsoil Permeability (Type) and Thickness Unsaturated

Zone

Karst

Features

High

Permeability

(Sand and

Gravel)

Medium

Permeability

(Sandy

Subsoil)

Low

Permeability

(Clayey

Subsoil/

Peat)

Sand and

Gravel

aquifers only

<30 radius

Extreme (E) 0 – 3.0m 0 – 3.0m 0 – 3.0m 0 – 3.0m -

High (H) >3.0m 3.0 -10.0m 3.0 – 5.0m > 3.0m N/A

Moderate

(M)

N/A >10.0m 5.0-10.0m N/A N/A

Low (L) N/A N/A >10m N/A N/A

Notes: N/A Not Applicable:

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Groundwater Vulnerability


Figure 8.7 A

Scale @ A3:


Client:

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Project Director:



1:50,000

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Keenagh



NOTES


Groundwater vulnerabilityExtremeHighLowModerateWaterExtreme - rock clost to surface

January 2019


LegendRiver

County BoundaryPlanning Application Boundary

Proposed Turbine Locations


445

Groundwater Usage

According to Longford County Council and Irish Water, there are two groundwater boreholes used as part

of the Lanesborough public water scheme (PWS).

Lisrevagh borehole, is located 7.3 km to the east of the development and abstracts groundwater for use

in the Lanesborough public water supply scheme. The Lanesborough ESB borehole, which is located

4.5km to the west of T3, abstracts groundwater at Lanesborough. Zones of Contribution (ZOCs) were

delineated for the EPA in 2011. The ZOC of a groundwater source is effectively a groundwater catchment.

They are influenced by the hydrogeology of a given area, and are determined from the considerations of:

• The total outflow at the source;

• The recharge to the associated groundwater flow system;

• Groundwater flow directions and gradients; and

• Subsoil and bedrock permeabilities.

No turbine is located within 1km of the Public Water Supply ZOCs. These abstraction points and zones

of contribution are included in Appendix 8.2. According to the GSI, there are no domestic wells within

0.25km of the turbines or borrow pits.

Groundwater Flow

On a regional scale, the groundwater flow direction is generally a subdued reflection of surface water

drainage. Therefore, on a regional scale, the groundwater flow is considered to be towards the

surrounding tributaries and the large rivers located to the east (Ballynakill River), and west (River Lough

Bannow and River Derrykeel) of the proposed wind farm. Limited recharge to groundwater is likely to

occur due to the low permeability peat, marl and till deposits on the site. To the north of the proposed

development at Derryaroge, a 500m long, 3m deep bedrock exposure of well bedded mid grey

fossiliferous limestones and calcareous shales occurs in a drainage ditch. No significant groundwater

discharges or karst features occur at this location. No large springs (>100m3/day) occur on the three bog

sites. Local groundwater flow discharges to the local streams and drainage ditches in the area.

Based on the measured groundwater levels in 2017 and 2018, groundwater flow is towards the Lough

Bannow Stream and internal drainage ditches (40 to 41mOD). The groundwater levels at the proposed

wind farm (42 to 44 mOD) are below the Cordara and Fortwilliam turlough level (45-47mOD). Therefore,

it is not possible for groundwater to discharge to the turlough area. Groundwater on site discharges to


446

the site’s arterial drainage network. Surface water discharge at Derryadd is to Lough Bannow Stream

and Ballynakill River. A conceptual site model is included below in Figure 8.8.

Further to the west of the proposed development (>3.5km), a karstic groundwater system has developed

on a limestone plateau area, overlain by shallow soils and bare rock. Where soils are thin or absent the

epikarst layer (i.e. the upper or shallow part of a karst system, in which water is stored before it percolates

to underlying aquifers) is well developed. Most groundwater flows occur in an epikarstic layer a couple of

metres thick. Conversely where deep soils occur, the karstification is typically limited. Deeper

groundwater flow can occur in areas associated with faults or dolomitisation.

Figure 8.8: East-West Conceptual model between Turbine 17 and Fortwilliam turlough

Turbines T18-T24 are located on Dinantian Sandstones, Shales and Limestones of the Keel Inlier, which

is part of the Inny GWB. This inlier is bounded to the southeast by a zone of normal step faults,

downthrowing to the southeast. Given the non karstic geology underlying these turbines there is no

connectivity with the turloughs located >7km the east. Groundwater in this area discharges to the sites

arterial drains and to the Ballynakill stream. As outlined previously due to distance, aquifer type and

groundwater flow directions there is also no complete source- pathway – receptor connectivity, with T1

to T17 turbines.


447

8.4 POTENTIAL IMPACTS

8.4.1 Introduction

This section addresses the potential impacts on the hydrological and hydrogeological environment of the

proposed wind farm. The potential impacts may comprise direct and indirect impacts on the quality of

surface waters and groundwater, and on potential the increased volume of surface water flow. The

hydrological and hydrogeological assessment identified water sensitive waterbodies downstream from

the proposed infrastructure works.

The current proposals for all construction activities and operational infrastructure were reviewed to

identify activities likely to impact upon identified water bodies including water courses within and remote

from the site. Following the identification of sensitive waterbodies, the extent and severity of potential

construction, operational and decommissioning impacts were evaluated considering all proposed control

measures included in the project design.

Sensitivity of Receptors

The sensitivity of an environmental receptor is based on its ability to absorb an impact without perceptible

change. The hydrological environment is of moderate sensitivity for receptors draining to Shannon via

hydrological links. The EPA has found the water quality in the receiving waters to be moderate (Q3 to

Q3-4). There are no ‘Registered Protected Areas‘(RPA) nutrient sensitive rivers in

hydrological/hydrogeological connection with the proposed development. There are no RPA habitat rivers

in hydrological/hydrogeological connection with the proposed development. There are no RPA nutrient

sensitive lakes and estuaries in hydrological/hydrogeological connection with the proposed development

and there are no RPA shellfish/pearl mussel areas along the proposed development.

8.4.2 Do Nothing Effects

If the wind farm development does not proceed, the proposed development sites will remain as a peat

production site. In areas where agriculture and forestry are present, normal agricultural and forestry will

continue to occur into the future. There are no significant impacts to the hydrological and hydrogeological

environment in a do nothing scenario.

8.4.3 Potential Effects - Construction

Construction Activities

The construction phase of the development will involve the following key activities that may have potential

impacts on surface water and groundwater conditions:


448

• Earthworks related to:

o Temporary site compound construction;

o Construction of access tracks and passing bays;

o Construction of amenity roads

o Construction of turbine foundations and turbine hardstands;

o Construction of either Substation Option A or Option B

o Excavation and construction of angle masts

o Laying of underground electrical cabling/construction of overhead line;

o Borrow Pit excavations; and

o Stockpiling material.

• Handling and storage of hydrocarbons, concrete and other potential water pollutants.

The construction of the temporary site compound areas, site access tracks, turbine foundations, turbine

hardstands, laying of underground electrical cabling, borrow pits, drainage channels will involve the

removal of vegetation and forestry and the excavation of peat, marl and mineral subsoil. Exposed and

disturbed ground may increase the risk of erosion and subsequent sediment laden surface water runoff.

The release of suspended solids is primarily a consequence of: the physical disturbance of the ground

during the construction phase, if not correctly compacted. Incorrect site management of earthworks and

excavations could, therefore, lead to loss of suspended solids to surface waters as a consequence of the

following activities:

• Soil stripping, if necessary, to construct the access roads, passing bays, site compounds, turbine

foundations, hardstands, borrow pits, turbines/hardstanding/roads and substations (A&B);

• Run-off and erosion from soil stockpiles (prior to reinstatement/profiling/side casting);

• Dewatering of excavations for turbine foundations, angle mast foundations and borrow pits

(where necessary). The result of increased sediment loading to watercourses is to degrade water

quality of the receiving waters and change the substrate character.

Hydrology and Hydrogeological Impacts

Based on construction phase activities outlined above, the potential hydrological and hydrogeological

impacts can be summarised as follows:

• Surface water quality impacts;

• Surface water flow alterations; and

• Groundwater flow and quality impacts.


449

There is potential for an increase or a decrease in runoff due <2ha of permanent impermeable surfaces

(e.g. turbine foundations) and 33ha permeable surfaces. The proposed development represents 2.7% of

the three peatland areas.

This could potentially reduce the infiltration capacity of the soils in areas where earthworks are undertaken

and increase the rate and volume of direct surface runoff. Surface water control measures are

incorporated into the design of the proposed development. A slight reduction in peak rainfall is anticipated

where areas of peat are replaced with gravel trackways and gravel hardstand areas. The potential for an

increase in runoff to streams is limited as surface water runoff is already controlled and managed in

accordance with the IPC licence and site management procedures.

Pre-mitigation, the potential construction impact varies from a slight negative to slight beneficial short-

term impact.

There is a potential impact as a result of dewatering borrow pits and turbine bases on site. Borrow pit

areas for example, are up to 10m deep, will encounter groundwater. Groundwater inflows may need to

be pumped, resulting in short term localised drawdown of the water table and discharges to the surface

water channels. There are no wells within 250m of the proposed borrow pit or turbine locations.

During construction of the wind farm, there is a risk of accidental pollution incidences from the following

sources:

• Spillage or leakage of oils and fuels stored on site;

• Spillage or leakage of oils and fuels from construction machinery/vehicles;

• Spillage or leakage of wastewater from temporary site facilities;

• Spillage of oil or fuel from refuelling machinery on site; and

• Spillages arising during the use of concrete and cement for turbine foundations and hardstanding

areas.

There will be a risk of pollution from site traffic through the accidental release of oils, fuels and other

contaminants from vehicles. Concrete (specifically, the cement component) is highly alkaline and any

spillage to a local watercourse would be detrimental to water quality and fauna and flora.

Borrow Pit Excavations

It is proposed that much of the material volume will be obtained from on-site borrow pits. The potential

borrow pits will be excavated to provide fill material for roads, cycle tracks, hardstanding, upfill to


450

foundations and temporary compounds. The borrow pits are located within Derryadd Bog towards the

centre of the site and are at advantageous locations with regards to hauling materials within the site.

Temporary pumping of groundwater will be required to facilitate excavation. The hydraulic permeability

of the unconsolidated material interpreted from the data recorded from the test and is included in

Appendix 8.3. The average permeability based on a number of different interpretations of the data for

each shallow borehole is listed below:

RC4 : K(average) = 0.08m/day

RC3: K(average) = >0.12m/day

Based on the slug test data, the Transmissivity is at the lower range at 5 m2/day. However, slug tests are

affected borehole conditions and only stress a small volume of the aquifer (generally few feet around the

well). Due to the presence of fractures (but a general absence of dolomite) in the boreholes and due to

the potential variability within the formation, a conservative figure of 20 to 50 m2/day is used.

Based on the above principles and a Transmissivity value of 20 to 50 m2/day; required groundwater

discharge rates of 1,800 to 2,300 m3/day are obtained. The empirical estimate calculates a 0.1m

drawdown at 250m. There are no wells within 250m of the borrow pits. Therefore, the potential for effect

is short term and negligible.

The borrow pits will be reinstated using two material sources (a) overburden from the opening of the

borrow pits, and (b) mineral soils excavated elsewhere on the site that cannot be reused in wind farm

construction.

Excavation for Turbine Foundations

The material encountered in the trial pits excavated at each turbine location was generally soft to very

soft and not capable of supporting the applied loads from a wind turbine. Deeper excavations to more

competent material will be required to construct the turbine foundations. Additional fill material will be

needed to upfill the excavation to the levels required for the wind turbines foundations. These excavations

have the potential to have a slight negative short-term effect on the surface water environment.

Preliminary volume calculations provide an approximate estimation of fill required for all of the turbine

foundations assuming none are piled. It is estimated as 27,000m3 of compacted material which is

equivalent to 35,000m3 of un-compacted material allowing for bulking during transportation.


451

Excavation for Hardstanding Foundations/Temporary Construction Compounds

The environmental effects of the construction of the hardstanding foundations are similar to that of the

turbine foundations as discussed in Section 7.4.2.7. Volume calculations provide an approximate

estimation of fill required for all the hardstanding foundations. It is estimated as 215,000m3 of compacted

material, which is equivalent to 280,000m3 of un-compacted material allowing for bulking during

transportation. For the compounds, it is estimated that 25,000m3 of compacted material, which is

equivalent to 32,500m3 of uncompacted material allowing for bulking during transportation will be

required. It is proposed to install culverts anywhere the proposed road layout intersects a stream. The

only stream crossing is located to the south of the Derryadd site (26_593) and crosses a man-made

drainage channel/stream. The channel is a constructed 3m wide and constructed within peat. Culverts

will be of a size adequate to carry expected peak flows.

These excavations have the potential is considered to have slight negative short-term effect on the

surface water environment.

Excavation for Substation Foundations

The construction of a substation at either Option A or Option B will require removal of topsoil and subsoil

to a competent founding layer and upfilling with concrete or structural fill to the required finished floor

level. Ground investigations at potential substations locations A, and B, have only been undertaken for

the purposes of the EIAR and have been used to inform the depth of excavation and upfill required.

8.4.3.6.1 Substation Option A

Preliminary volume calculations provide a rough estimation of fill required for the foundations for

substation, assuming spread foundations are used where they are founded on competent material. This

is estimated as 63,000m3 of compacted material which is equivalent to 82,000m3 of un-compacted

material allowing for bulking during transportation. The potential impact is considered to have negligible

to slight negative short-term effect on the surface water environment.

8.4.3.6.2 Substation Option B

Similar to substation A, preliminary volume calculations provide a rough estimation of fill required for the

foundation of substation B assuming spread foundations are used where they are founded on competent

material. The founding layer is anticipated to be slightly shallower at this location. This is estimated as

25,000 m3 of compacted material which is equivalent to 32,500m3 of un-compacted material allowing for

bulking during transportation. The potential impact is considered to have negligible to slight negative

short-term effect on the surface water environment.


452

8.4.4 Potential Effects - Operation

Do Nothing Effects

If the wind farm development does not proceed, the proposed development site will remain as a peat

production site. In areas where agriculture and forestry are adjacent or within the site, normal agricultural

and forestry will continue to occur into the future. There are no significant impacts to the hydrological and

hydrogeological environment in a do nothing scenario.

Turbines, Hardstanding, Temporary Construction Compounds, Met Masts, Roads

As the site is current a peat extraction site, the installation of permanent infrastructure could result in a

slight decrease in runoff during the operational phase of the wind farm. The proposed development

represents 2.7% of the three peatland areas.

The presence of hardstanding areas and the additional water control measures is likely to have a slight

long-term beneficial impact in the water quality in particular ammonium and suspended solids.

It is estimated that 2.7% (51.8 hectares) in total of the existing bog will be developed for the proposed

wind farm infrastructure. The principal behind sustainable drainage devices is to reduce the quantity of

discharge from developments to predevelopment flows and to improve the quality of run-off from

proposed developments. The sustainable drainage devices will mimic existing greenfield runoff in terms

of volume, rate of runoff and quality of the runoff. In this case, it is proposed to decrease the quantity of

run-off to Greenfield rates by providing surface water attenuation lagoons. Attenuation lagoon details

shown on Drawing No. 10325-2006 to 13025-2013.

With regard to water quality impacts, there will be no direct discharges to the surface water environment

during the operational phase. Due to the nature of the development there will be vehicles periodically on

the site at any given time. The potential impacts are limited by the size of the fuel tank of the vehicles

using on the site. As a result, occasional/accidental emissions, in the form of oil, petrol or diesel leaks,

which could cause slight/negligible temporary and localised contamination of site drainage channels.

Substation Options

The potential operational effects of either Option A or B are effectively the same. The operation of the

proposed Substation (Option A or B) will require infrequent inspection and maintenance visits. Elements

of the electrical plant at the substation site (primarily transformers) may contain oil for insulation purposes.

The released hydrocarbons would have the potential to percolate to contaminate the surface water runoff


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and the surface water body into which the run-off discharges. The pre-mitigation impact is considered

slight negative.

The presence of occasional maintenance workers at the proposed substation will lead to the generation

of foul sewage from toilets and washing facilities. This foul sewage will be collected and tankered off-site

for disposal at a licensed waste water treatment facility. The potential for impact is slight to negligible and

short-term.

8.4.5 Magnitude and Significance of Impact –Construction and Operation

The magnitude of an impact includes the timing, scale, size and duration of the potential impact (pre-

mitigation). The magnitude criteria for hydrology/hydrogeology are defined as set out in Table 8.9 and

8.10 below.

Table 8.9: Magnitude and Significance of Hydrological Criteria – Construction Phase (Pre-mitigation)

Criteria Description Duration and

Frequency

of Effects

Significance

of potential

effect

Run-off regime Potential Increase in surface runoff

may be caused by impermeable

areas on site may give rise to a slight

increase in surface water flow locally

but is expected to have a negligible

impact on the volumetric flow rate of

downstream rivers.

Short term

and rarely

Slight negative

/ Slight

beneficial

Surface Water Quality No significant loss in water quality is

expected.

Short term

and

occasional

Slight negative

Groundwater Levels No significant change in groundwater

is expected. Slight localised

drawdown predicted at the borrow pit

locations. No ZOCs or wells within

250m of borrow pits or turbines.

Temporary

and

occasional

Negligible

Groundwater Quality No change in groundwater quality is

expected

Not

applicable

Negligible


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Table 8.10: Magnitude and Significance of Hydrological Criteria – Operational Phase (Pre -mitigation)

Criteria Description Duration and

Frequency of

Effects

Significance

of potential

effect

Run-off regime Increased surface runoff caused by

impermeable areas on site may give rise

to a slight increase in surface water flow

locally but is expected to have a slight

potential effect on the volumetric flow rate

of downstream rivers.

Long term and

rarely

Slight beneficial

/slight negative

Surface Water Quality No significant loss in water quality is

expected. A slight beneficial impact could

occur as a result of reduced runoff from

peatlands.

Long term and

rarely

Slight beneficial

to negligible

Groundwater Levels No significant change in groundwater is

expected.

Not applicable Negligible

Groundwater Quality No change in groundwater quality is

expected. No ZOCs or wells within 250m

of turbines. Rare potential fuel spills may

occur within the proposed development.

Short-term

and rarely

Negligible

Potential impacts are of slight/negligible significance.

8.4.6 Major Accidents /Disasters

As part of the requirements of the new EIA Directive, the applicant is requested to consider the “Expected

Significant Adverse Effects of the project on the environment deriving from the vulnerability of the project

to risks of major accidents and/or disasters which are relevant to the project concerned.”

It is clear from the directive that a major accident and/or natural disaster assessment should be mainly

applied to COMAH sites or nuclear installations. The propose project is not a COMAH or nuclear

installation, however the assessment is included for completeness. The starting point for the scope and

methodology of this assessment is that the Proposed Development will be designed, built and operated

in line with best international current practice and the type of project, as such, major accidents will be

extremely unlikely. The management of any potential environmental accidents will be managed through

the adoption of site best practises in the CEMP. A flood risk assessment was undertaken to determine

whether the site is at risk from extreme fluvial flooding events. This report is discussed in Section 8.3 and

concluded that the site is not at risk from extreme flooding. The potential for a significant spillage of


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hydrocarbons is limited on site. The risk of a serious spillage occurring on site is negligible.

Notwithstanding the negligible risk of serious spillage, additional spillage protection measures are

included in the Proposed Development. During a spillage event, the spill will be collected by the drainage

network and managed within the site boundary where it can be safely removed and treated/disposed.

Section 8.5 outlined mitigation measures in relation to potential contaminants.

It can be concluded that the risk of accidents associated with this development is very low and would not

cause unusual, significant or adverse effects on human health or the environment during the construction

or operational phase.

8.4.7 Cumulative Effects

Information on the relevant projects within the vicinity of the proposed development was assessed. The

information was sourced from a search of the local authorities planning registers, EPA website, planning

applications, EIS documents and planning drawings which facilitated the identification of past and future

projects, their activities and their potential environmental impacts. The projects considered in relation to

the potential for cumulative impacts and for which all relevant data was reviewed include those listed

below.

Lanesborough Power station -EPA Licence P0610-03

In December 2017 planning permission (Planning ref. 17/320) was sought to extend the capacity of the

Derraghan Ash Disposal Facility. Planning permission was granted for this increase by Longford County

Council on 28th March 2018. ESB applied to the EPA on 28th May 2018 for a review of IE Licence P0610-

02. The Environmental Impact Assessment Report (EIAR) and the Appropriate Assessment (AA)

Screening which accompanied the planning application was also submitted to the EPA with the

application for the IE review. The power station is located in Lanesborough town, 2km to the west of the

proposed wind farm. The ash facility is located 1.5km to the south west of Lough Bannow Bog in a

separate surface water catchment to the proposed development.

Mountdillon EPA Licence P0504-01

The proposed wind farm is located within an operating peat extraction site. An extensive network of

drainage channels is present throughout the peatland which is currently operated under IPC licence

P0504-01 Mountdillon bog group. Peat harvesting has reduced in the last 10 years with milled peat

production projected to cease in the coming years. Bord na Móna has published two documents. The

Strategic Framework for the Future Use of Peatlands published in 2011, which outlines the future potential

of the company’s land holding including factors affecting potential reuse opportunities. The second

document, entitled Biodiversity Action Plan 2016-2021, addresses peatland biodiversity management,

http://www.epa.ie/terminalfour/ippc/ippc-view.jsp?regno=P0504-01


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restoration and conservation. Rehabilitation of industrial cutover peatlands is a key objective of the Bord

na Móna Biodiversity Action Plan 2016-2021. The drainage regime proposed at the site is designed in

such a manner as to be integrated into the final rehabilitation plan for the site. In 2013, Bord na Móna

submitted draft rehabilitation plans for each of the Bord na Móna bogs, as per IPC Licence Condition 10

requirements. The plans were further updated in 2015, following rehabilitation trails. The main elements

required for rehabilitation post peat production are stabilisation of former bare peat areas largely attained

through natural processes of revegetation which may require enhancement by targeted management

such as fertiliser/ seeding; surface manipulation and/ or hydrological management (drain/ outfall

blocking). Following peat production these rehabilitation measures will be put in place at the site as

required. The likely outcome of these rehabilitation practises is that the site will become of greater value

to protected species, including the qualifying interest of local designated sites, e.g. breeding waders and

otters. It is proposed by Bord na Móna to incorporate the proposed development into the rehabilitation

plan, therefore it will not impede it.

Middleton House Solar Farm (Longford Co. Co. Planning Ref 18/35)

Planning permission Longford County Council register reference 18/35 – a grant of planning permission

issued to Harmony Solar on 15/08/2018 for a ten year permission for a solar farm on a site of

approximately 51.38 hectares consisting of the following: up to 216,000 m2 of solar photo-voltaic panels

on ground mounted steel frames to generate between 35MW to 50MW of electrical energy; substation

and control room and associated hard standing; 14 no. inverter/transformer stations; underground power

and communication cables & ducts; boundary security fence; CCTV cameras; upgraded internal access

tracks; new internal access tracks and associated drainage infrastructure; provision of passing areas on

lands adjacent to the L-11261 local road; access will be via the L-11261 local road through the upgrade

of an existing agricultural entrance and at the existing entrance to Middleton House; and temporary

construction compounds and all associated site services & works at the townlands of Middleton,

Ballycore, Treanboy and Newtown, near the village of Killashee, Co. Longford. Planning permission was

awarded on the 15/08/18. The proposed development area drains toward the Ballynakill stream.

Fisherstown Solar farm (Longford Co. Co. Planning Ref. 18/146)

Planning permission Longford County Council register reference 18/146 – a grant of planning for

development on the 26/08/18 at a site comprising lands within the property of the former Atlantic Mills

factory. The development will comprise the construction of a solar farm with an export capacity of

approximately 4MW comprising photovoltaic panels on ground mounted frames, with associated

infrastructure including a switch gear control room (to be developed at 1 of 2 location options on site. No

additional works proposed to the existing substation on site as part of this application), ducting and

electrical cabling, internal access roads, fencing and all associated site development works at

Fisherstown, Clondra, Co. Longford. Planning permission was awarded on the 24/08/18. The proposed


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solar farm development is located within the River Shannon catchment, >5 km upgradient of the proposed

wind farm.

Plans and Policies Considered as part of the Cumulative Assessment

The following key plans and policies were identified as having the potential to act in-combination with the

proposed development to affect the relevant European Sites, as per Table 3.3.

• Longford County Development Plan 2015 – 2021;

• River Basin Management Plan 2018 – 2021 (released in April 2018); and

• In 2013, Bord na Móna submitted draft rehabilitation plans for each of the Bord na Móna bogs,

as per IPC Licence Condition 10 requirements. The plans were further updated in 2015,

following rehabilitation trails.

Cumulative Impact Assessment

Cumulative effects can be defined as the additional changes caused by a proposed development in

conjunction with other similar developments124.It is similarly defined in the EIAR 2017 EPA guidance as

‘The addition of many minor or significant effects, including the effects of other projects, to create larger,

more significant effects.’ There are no existing or permitted wind farms in Co. Longford.

In relation to the Middleton House and Fisherstown Solar Farm the planning permission granted to these

two sites include the requirement for protective measures and arising from the separation distances (i.e.

1.5km and 5.9km respectively) between the developments cumulative effects are considered unlikely.

The discharges from the Bord na Móna bogs are and have been regulated and controlled by the EPA

under the IPC Licensing process. The IPC Licence has been examined and revised by the EPA, as

required, in line with the objectives of the WFD.

It is considered that there will be a slight/negligible potential impact on the water environment as a result

of Derryadd wind farm development during the construction and operational phase. It is considered that

there is no potential for significant impacts to result from the proposed development cumulatively with

other planned developments. Further details on the potential cumulative impacts on water quality and the

potential hydrological connectivity of the proposed development area with local ecological features (post

mitigation) are addressed in Chapter 6 of this volume of the EIAR.

124 SNH (2012) Assessing the cumulative impacts of onshore wind energy developments.


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8.4.8 Decommissioning

Decommissioning of the Proposed Development would result in the cessation of renewable energy

generation and the removal of infrastructural elements. These impacts have therefore been assessed as

similar to the construction phase and mitigation measures for the construction phase should also be

implemented during decommissioning.

Concerning the hydrological impacts, there is the potential for impact on a number of the receptors as a

result of removal of the infrastructure. Changes to the internal drainage could lead to localised erosion

and therefore changes in the morphological processes. This would be likely to have a low magnitude of

impact for the low sensitivity watercourses, resulting in a slight and short-term effect.

8.5 MITIGATION MEASURES

As outlined in Chapter 2, Description of the Proposed Development, the design of the proposed

development has considered a range of best practice construction measures which ensure avoidance of

impacts throughout the construction and operational phases. Additional measures have been developed

to mitigate the impacts identified in the preceding section.

8.5.1 Mitigation by Avoidance

In identifying and avoiding sensitive surface waters the proposed development has implemented

‘avoidance of impact’ measures. Mitigation by avoidance is viewed as part of the ‘Reasonable

Alternatives’ outlined in Chapter 3. Examples include locating fuel storage and construction compounds

>50 m upgradient of surface water streams.

A section of commercial forestry was avoided in Lough Bannow as part of the mitigation by avoidance.

Forestry felling activities have the potential to cause temporary and local damage to soils and may impact

on water quality, through increased erosion rates, sedimentation and nutrient losses. Furthermore, the

wind farm design complied with Policy WD4 in the Longford County Development Plan 2015 – 2021, that

stipulates that wind farm developments should not be located within 150m of lakes and rivers.

8.5.2 Mitigation by Prevention and Reduction

A number of mitigation measures are outlined below and are considered as in-built to the design of the

project. These mitigation measures are a combination of measures to comply with legislation and best

practice construction methods to be implemented in order to prevent water (surface and groundwater)


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pollution. Examples of these measures are the storage of potentially polluting materials in fully bunded

tanks and controlling / reducing runoff from hardstand areas.

8.5.3 Mitigation Measures - Construction Phase

In order to mitigate potential impacts during the construction phase, best practice construction methods

will be implemented in order to prevent water (surface and groundwater) pollution. A Construction

Environmental Management Plan (CEMP) was developed for the project to ensure adequate protection

of the water environment. All personnel working on the project will be responsible for the environmental

control of their work and will perform their duties in accordance with the requirements and procedures of

the CEMP.

During the construction phase, all works associated with the construction of the wind farm will be

undertaken with due regard to the guidance contained within CIRIA Document C741 ‘Environmental

Good Practice on Site’ (CIRIA, 2015).

All mitigation and management measures outlined hereunder will be incorporated into the Surface Water

Management Plan, (Appendix 8.4). Mitigation measures are incorporated into the CEMP and will be

incorporated into the specification for the Civil Engineering Works contract. The implementation of the

Surface Water Management Plan will be overseen by the appointed Site Ecologist and the Project

Manager and will be regularly audited throughout the construction phase. The Project Manager will be

required to stop works on site, if he/she is of the opinion that a mitigation measure or corrective action is

not being appropriately or effectively implemented.


As stated previously, to maximise the erosion and sediment control benefits of natural vegetation soil

cover, stripping of peat is to be kept to a minimum and confined to construction areas only. Where

practical, construction works will be staged to minimise the extent and duration of disturbance, e.g. plan

for progressive site clearance, only disturbing areas when they are scheduled for current construction

work.

To minimise any impact on the underlying subsurface strata from material spillages, all oils and solvents

used during construction will be stored within specially constructed dedicated bunded areas. Refuelling

of construction vehicles and the addition of hydraulic oils or lubricants to vehicles will take place in a

designated area of the site, away from surface water gullies or drains. Spill kits and hydrocarbon

absorbent packs will be stored in this area and operators will be fully trained in the use of this equipment.


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All construction waste will be sorted and stored in on-site skips, prior to removal by a licensed waste

management contractor.

Concrete

Concrete is required for the construction of the turbine bases and foundations. After concrete is poured

at a construction site, the chutes of ready mixed concrete trucks must be washed out to remove the

remaining concrete before it hardens. Wash out of the main concrete bottle will not be permitted on site;

wash out is restricted only to chute wash out. Wash down and washout of the concrete transporting

vehicles will take place at an appropriate facility offsite i.e. at the premises of the concrete supplier.

The best management practice objectives for concrete chute washout are to collect and retain all the

concrete washout water and solids in leak proof containers or impermeable lined wash out pits, so that

the wash material does not reach the soil surface and then migrate to surface waters or into the ground

water. The collected concrete washout water and solids will be emptied on a regular basis.

Photo 1 and 2 Example Photos of Concrete Washout On Site

Fuels and Chemicals

With regard to on-site storage and handling of potentially pollutant materials:

• Fuels and chemicals will be stored within bunded areas as appropriate to guard against potential

accidental spills or leakages. The bund area will have a volume of at least 110 % of the volume

of such materials stored;

• All on-site refuelling will be carried out by a trained competent operative.

• Mobile measures such as drip trays and fuel absorbent mats will be used during all refuelling

operations;


461

• No refuelling will take place within 50 m of any watercourse;

• All equipment and machinery will have regular checking for leakages and quality of performance

and will carry spill kits;

• Any servicing of vehicles will be confined to designated and suitably protected areas such as

construction compounds;

• Additional drip trays and spill kits will be kept available on site, to ensure that any spills from

vehicles are contained and removed off site.

Erosion and Sediment Control

As outlined above, if not correctly managed, earthworks can lead to loss of suspended solids to surface

waters. The main factors influencing the rate of soil loss and subsequent sediment release include:

• Climate;

• Length and steepness of slopes;

• Soil erosion potential;

• Soil Vegetation/cover;

• Duration and extent of works; and

• Erosion and sediment control measures

Runoff will be maintained at greenfield runoff rates. The layout of the development has been designed to

collect surface water runoff from hardstanding areas within the development and discharge to associated

surface water attenuation lagoons adjacent to the proposed infrastructure. It will then make its way into

the existing field drains and existing settlement ponds infrastructure before being discharged through

existing discharge points by pump or gravity flow. From here the water will outfall at the appropriate

Greenfield run off rates.


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Figure 8.9: Proposed and existing drainage layout

It is proposed, that during the ground clearance of the proposed development, water control measures

will be implemented by the contractor to limit the volume of water that requires treatment. The contract

documents and works requirements will specify the necessity for the contractor to take all precautions

needed to prevent sedimentation of water channels. Contractors will be required to specify temporary

sediment control measures (i.e. grit traps or similar) to be employed along with water attenuation during

construction.

Erosion and sediment control measures include:

• Minimisation of soil exposure, by controlling, in so far as is practical, where and when peat is

stripped;

• During the side casting of peat, silt fences, straw bales and/or biodegradable geogrids will be

used to control surface water runoff from the storage areas, if required; and

• All surface water run-off from the development will pass through settlement ponds. It is proposed

to locate settlement ponds immediately downstream of the proposed infrastructure including each

hardstand and along all site access tracks.

The settlement pond design is based on primary settling out of suspended solids from aqueous

suspension. The theory behind the design of the settlement lagoons is the application of Stoke’s Law.

The settlement lagoons have been designed to provide sufficient retention time and a low velocity

environment to allow suspended solids of a very small particle size to fall out of suspension prior to

allowing the water to outfall to the receiving environment.


463

Settlement ponds will be located appropriately where required, in line with and will be installed

concurrently with the formation of the road. Settlement ponds will be located as close to the source of

sediment as possible and as far as possible from the buffer zones of existing watercourses. The minimum

buffer zone width will be 15m as outlined above.

Settlement ponds will be regularly cleaned/maintained to provide effective and successful operation

throughout the works. Outfalls and ditches will be cleaned, when required, starting up stream with the

outfalls blocked temporarily prior to cleaning.

Sediment/silt removed via the contractor from ponds will be deposited at suitable locations on site, away

from watercourses. It is proposed to deposit peat onto the profiled peat adjacent to roadways. Machine

access is required to enable the accumulated sediment to be excavated.

• Regular inspection and maintenance of Settlement ponds and drains;

• Settlement pond maintenance and/or cleaning will not take place during periods of extended

heavy rain;

• Settlement ponds will be clearly marked for safety;

• Settlement ponds will be constructed on even ground and not on sloping ground and where

possible will discharge into vegetation areas to aid dispersion; and

• The settlement ponds will be monitored closely over the construction timeframe to ensure that

they are operating effectively.

All stockpiled material will be side cast, battered back and profiled to reduce the rainfall erosion potential.

The stockpiling of materials will be carefully supervised as per the mitigation measures listed in Chapter

7, Lands, Soils and Geology.

Traffic on site will be kept to a minimum. No haul roads will be used other than the proposed site tracks.

Where haul roads pass close to watercourses, silt fencing will be used to protect the streams.

Temporary Site Compound Construction

During the construction phase, five temporary site compounds will be required. Temporary on-site toilet

facilities (chemical toilets) will be used. These will be sealed with no discharge to the surface water or

groundwater environment adjacent to the site.


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Surface Water Flow and Watercourse crossings

Potential impacts on surface water flow during the construction phase of the wind farm are mitigated by

the proposed drainage design which has been designed to minimise disturbance to the current

hydrological regime by maintaining diffuse flows.

It is proposed to install culverts anywhere the proposed road layout intersects a stream or main drain.

Culverts are to be of a size adequate to carry expected peak flows. Culverts will be installed to conform,

wherever possible, to the natural slope and alignment of the stream or drainage line. Where required,

culverts will be buried at an appropriate depth below the channel bed and the original bed material placed

in the bottom of the culvert. Embedded culverts should be buried to a depth of 0.3m or 20% of their height

(whichever is greatest) below the bed.

No instream works shall be carried out without the written approval of Inland Fisheries Ireland (IFI). IFI

will be given sufficient notice before pre-approved in-stream works commence. There will be no

discharge of suspended solids or any other deleterious matter to watercourses. Water crossings are to

be constructed in accordance with the requirements of the Office of Public Works (OPW) Section 50

Consent requirements and in accordance with the CEMP.

Crossing construction will be carried out, in so far as is practical, with minimal disturbance to the

stream/drainage bed and banks. If they have to be disturbed, all practicable measures will be taken to

prevent soils from entering the watercourse. Cement and raw concrete will not be spilled into

watercourses. Where practicable, crossings should be adequately elevated with low approaches such

that water drains away from the crossing point. Earth embankments constructed for bridge approaches

must be protected against erosion e.g. by re-vegetation or rock surfacing etc.

Borrow Pits

The mitigation strategies for the borrow pits follow similar procedures as the excavations for turbine and

hardstanding areas. Interceptor cut-off drains around the borrow pits will be provided to divert overland

flows and prevent these flows from entering the borrow pits. These flows will discharge diffusely overland,

creating a buffer before entering the existing surface water management infrastructure.

Substation Options A and B

The mitigation strategies for the substation foundations follow similar procedures as the excavations for

turbine and hardstanding foundations, see Section 8.5.1.17.5.2.6. All works will be monitored by suitably

qualified and experienced geotechnical engineer or engineering geologist.


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Major Accidents. Disasters



phase. No specific mitigation measures are required.

8.5.4 Mitigation Measures - Operational Phase

The following mitigation measures will be implemented during the operational stage.


Any vehicles utilised during the operational phase will be maintained on a weekly basis and checked daily

to ensure any damage or leakages are corrected. The potential impacts are limited by the size of the fuel

tank of vehicles used on the site.

Borrow Pits

There are no proposed borrow pit mitigation measures required for the operational phase.

Substation Options

Within the selected substation, all fuel will be stored in bunded areas. The bund capacity will be sufficient

to accommodate 110% of the largest tank’s maximum capacity or 25% of the total maximum capacities

of all tanks, whichever is the greater. The exception to this being double walled tanks equipped with leak

detection, which do not require additional retention.

A hydrocarbon interceptor will be installed at the proposed substation site with regular inspection and

maintenance, to ensure optimal performance.

Given the requirement for sanitary facilities during occasional operation and maintenance works,

wastewater effluent will be directed to an onsite holding tank, from where it will be tankered off site to a

suitably licensed waste water treatment plant.

Based on the above assessment, there are no significant cumulative or in combination effects on the

water/groundwater environment. Within the National River Basin Management Plan 2018 – 2021

(released in April 2018), extractive or anthropogenic pressures are not identified as a significant pressure

on a catchment scale basis. As is detailed in the River Basin Management Plan 2018 – 2021, Bord na

Móna is in the process of phasing out the extraction of peat for energy production by 2030. Bord na Móna

expects to stabilise and rehabilitate cutaway bogs and will look to implement best-available mitigation

measures to manage water quality while the phasing-out process is taking place Commercial peat


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extraction has decreased at the three bogs since the 2000’s. The surrounding peatlands will continue to

be managed in accordance with their relevant EPA IPC Licences.

Major Accidents. Disasters



phase. No specific mitigation measures are required.

8.5.5 Monitoring

It is recommended that local surface water features in the immediate vicinity of the site boundary are

monitored pre-construction and during construction to take account of any variations in the quality of the

local surface water and groundwater environment as a result of activities related to the proposed

development.

Inspections and maintenance are critical after prolonged or intense rainfall while maintenance will ensure

maximum effectiveness of the proposed measures. A programme of inspection and maintenance will be

designed and dedicated construction personnel assigned to manage this programme. A checklist of the

inspection and maintenance control measures will be developed and records kept of inspections, and

maintenance.

Monitoring requirements that are stipulated under the IPC licence for the peatlands will continue to be

fulfilled for the lifetime of the licence. During the construction phase, field testing and laboratory analysis

of a range of parameters should be undertaken at adjacent watercourses, specifically following heavy

rainfall events (i.e. weekly, monthly and event based). The monitoring will be completed at the locations

and for the parameters already specified in the IPC Licence. Monitoring proposals are included in the

CEMP, attached as Appendix 2.2.

8.6 RESIDUAL IMPACTS

The following conclusions can be drawn in relation to surface water and groundwater:

• The site drains to a number of tributaries surrounding the site boundary, primarily to tributaries of

the River Shannon;

• The site is underlain predominantly by low permeability shallow peat, marls, lacustrine/alluvial

soils and limestone tills;


467

• Man-made drains are located throughout the site and will continue to operate as part of the

existing water management system on site. The proposed drainage plan will further enhance the

water management at this location;

• The site is generally low lying and flat with very low slope gradients and consequently has a low

risk due to changes caused by the development on the hydrological regime;

• Water quality in the immediate area of the site is moderate and is consistent with the expected

natural water quality for an environment. The water quality reported by the EPA downstream of

the site is of poor/moderate status; and

• The site overlies both locally important and regionally important aquifers of Low to High

Vulnerability.

The residual impacts on the surrounding water quality, hydrology and existing drainage regime at the site

are considered to be negligible and short term in nature. The existing on-site drainage system will remain

active during construction and operation of the proposed wind farm and will be enhanced by a proposed

drainage plan that has been designed for this development.

The construction timescale of activities within the site will be phased and short-term in duration and,

thereafter, the only activities within the site that will be associated with maintaining existing drains,

ongoing maintenance and monitoring during the operational phase. There are no significant long-term

impacts.

8.6.1 Cumulative Effects

There are no significant cumulative effects as a result of the proposed development in relation to water

environment.

8.7 REFERENCES

Bouwer, Herman and Rice, R.C., 1976, A slug test for determining hydraulic conductivity of

unconfined aquifers with completely or partially penetrating wells, Water Resources Research

12(3) 423–428.

CIRIA C741 ‘Environmental Good Practice on Site’. (CIRIA, 2015)

CIRIA C750 Groundwater Control – Design & Practice (2016)

CIRIA C648 Control of Water Pollution from Linear Construction Projects: Technical Guide (CIRIA,

2006);

CIRIA C649 Control of Water Pollution from Linear Construction Projects: Site Guide (CIRIA.

2006);


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CIRIA C532 ‘Control of Water Pollution from Construction Sites, Guidance for Consultants and

Contractors’ (CIRIA. 2006);

Department of the Environment, Heritage and Local Government (2006) Wind Energy

Development Guidelines for Planning Authorities

Department of Communications Climate Action and Environment (2017) preferred draft approach

- Review of the Wind Energy Development Guidelines 2006

Department of Housing, Planning and Local Government (2018) - River Basin Management Plan

2018-2021

Environmental Protection Agency (2002). Guidelines on the Information to be contained in

Environmental Impact Statements

Environmental Protection Agency (2015). Revised Guidelines on the Information to be contained

in Environmental Impact Statements

Environmental Protection Agency (2017). EPA Catchments Mapping Portal

https://www.catchments.ie/maps/ (Accessed July 2018)

Environmental Protection Agency (2017). Draft Guidelines on the Information to be contained in

Environmental Impact Statements

Environmental Protection Agency (2017). EPA Envision Mapping Portal http://gis.epa.ie/Envision

(Accessed July 2018)

Environmental Protection Agency (2017). Flow and Water Level Measurements Portal

http://www.epa.ie/hydronet/#Water%20Levels (Accessed July 2018)

Environmental Protection Agency (2017). Water Quality Monitoring Database and Reports Portal

http://www.epa.ie/pubs/reports/water/waterqua/ (Accessed July 2018)

EPA Advice Notes on Current Practice in the Preparation of Environmental Impact Statements

(EPA, 2017)

Fetter, C.W., 1994, Applied Hydrogeology, Third Edition: Macmillan, NY, 691 p.

GSI (1998) GSI Groundwater Newsletter No. 33

Forest Service, 2000a. Forest Harvesting and the Environment Guidelines. Department of

Agriculture, Fisheries and Food.

Forest Service, 2000b. Forest and Water Quality Guidelines. Department of Agriculture, Fisheries

and Food.

Kruseman & deRidder, (2nd Ed. 1990). Analysis and Evaluation of Pumping test Data.

https://www.catchments.ie/maps/

http://gis.epa.ie/Envision

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in and Adjacent to Waters

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Glossary

Aquifer A subsurface layer of layers of rock or other geological strata of sufficient porosity and

permeability to allow either a significant flow of groundwater or the abstraction of significant

quantities of groundwater [Water Framework Directive (2000/60/EC)].

Hydraulic conductivity [m/d] is an expression of the rate of flow of a given fluid through unit area

and thickness of the medium, under unit differential pressure at a given temperature. In subsoils,

intergranular permeability dominates, whilst in rock, fissure permeability (via fractures and bedding

discontinuities) dominates in limestone bedrock in Ireland.

http://www.met.ie/

https://www.npws.ie/protected-sites/sac/002299

http://www.floodmaps.ie/

https://www.osi.ie/products/professional-mapping/historical-mapping/



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Specific Capacity Q/s [m³/d/m] The rate of discharge of water from the well divided by the

resulting drawdown on the water level within the well

Specific yield (%) indicates the amount of water released from an aquifer due to drainage. By

definition, it is always less than porosity due to retention of some groundwater by the subsoil/rock.

Transmissivity T [m²/d] Transmissivity relates to the ability of an aquifer to transmit water through

its entire thickness.

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